BMN673 exerted an anti-MPN effect in vivo. (Panel A) Experimental model. Lethally irradiated C57BL/6 recipient mice were injected with a 1:1 mixture of 10⁶ GFP+JAK2(V671F) and 10⁶ wild-type bone marrow cells. Five weeks later, mice were treated with vehicle (C), hydroxyurea (H; 30 mg/kg twice daily IP), ruxolitinib (R; 30 mg/kg twice daily oral gavage), BMN673 (B; 0.33 mg/kg IV), H+R, H+B, R+B, and H+R+B for 3 weeks. Percentage of GFP+JAK2(V617F) was measured in (panel B) bone marrow cells, (panel C) splenocytes, and (panel D) peripheral blood leukocytes; (panel E) number of GFP+JAK2(V617F) Lin⁻Sca1⁺c-Kit⁺ (LSK) cells per 10⁶ bone marrow cells was calculated, too. *P < .05, **P < .05, and ***P < .05 when compared with control, single treatment, and double treatment, respectively, from 6 to 7 mice using the Student t test.